This invention relates in general to drive train assemblies for transferring rotational power from an engine to an axle assembly in a vehicle. In particular, this invention relates to a cover assembly for protecting the surfaces of a slip yoke during manufacturing and assembly of such a vehicle drive train assembly.
In most land vehicles in use today, a drive train assembly is provided for transmitting rotational power from an output shaft of an engine/transmission assembly to an input shaft of an axle assembly so as to rotatably drive one or more wheels of the vehicle. To accomplish this, a typical vehicular drive train assembly includes a hollow cylindrical driveshaft tube. A first universal joint is connected between the output shaft of the engine/transmission assembly and a first end of the driveshaft tube, while a second universal joint is connected between a second end of the driveshaft tube and the input shaft of the axle assembly. The universal joints provide a rotational driving connection from the output shaft of the engine/transmission assembly through the driveshaft tube to the input shaft of the axle assembly, while accommodating a limited amount of angular misalignment between the rotational axes of these three shafts.
Not only must the drive train assembly accommodate a limited amount of angular misalignment between the engine/transmission assembly and the axle assembly, but it must also typically accommodate a limited amount of axial movement therebetween. A small amount of such relative axial movement frequently occurs when the vehicle is operated. To address this, it is known to provide one or more slip yoke assemblies in the drive train assembly. Slip yoke assemblies have a pair of splined members which provide a rotational driving connection between the components of the drive train assembly, while permitting a limited amount of axial misalignment therebetween. A typical slip yoke assembly includes a slip yoke having a yoke portion and a cylindrical end portion. The end portion is typically hollow and includes a plurality of internal splines. The internal splines mate with external splines formed on a shaft, such as may be secured to an end of a driveshaft tube in the drive train assembly.
As is well known in the art, most slip yoke assemblies are provided with one or more seals to prevent the entry of dirt, water, and other contaminants into the region where the splined members engage one another. Such contaminants can adversely affect the operation of the slip yoke assembly and cause premature failure thereof. Typically, such a seal includes a flexible lip portion that engages the outer cylindrical surface of the end portion of the slip yoke to prevent contaminants from entering into the inner splined region where the slip yoke engages with a mating splined component of the drive train assembly. To insure a reliable seal, therefore, it is usually important for the outer cylindrical surface of the end portion of the slip yoke to be generally smooth and free from relatively large surface irregularities, such as nicks and dents.
To accomplish this, the outer cylindrical surface of the end portion of the slip yoke is usually machined precisely during manufacture to achieve the desired smooth shape. Thereafter, it has been found to be desirable to protect this precisely machined surface during the subsequent processing and assembly steps involved in manufacture of the drive train assembly. In the past, to protect this precisely machined surface, it is known to use a one piece, cup-shaped cover that slips over and protectively covers the end portion of the slip yoke, including the outer cylindrical surface thereof. The cover is generally tubular in shape, having a closed end and an opened end. The cover is installed on the yoke by inserting the end portion of the slip yoke through the opened end of the cover. Thus, the cover protects the outer surface of the end portion of the slip yoke. The closed end of the cover extends over the open splined end of the slip yoke to prevent contaminants from entering therein.
Although this type of cover has functioned satisfactory in the past, it is sometimes desirable to obtain access to the splined interior of the end portion of the slip yoke during the various processing and assembly steps involved in manufacture of the drive train assembly while continuing to protectively cover the precisely machined outer surface of the slip yoke. For example, it may be desirable to insert a tool fixture into the internal splined region of the end portion of the slip yoke to hold the slip yoke in position during a machining or assembly procedure. In the past, the entire cover was simply removed (and possibly discarded) at this intermediate step of assembly, when access to the interior splined portion of the slip yoke was required. However, removal of the cover also undesirably exposes the precisely machined outer surface of the slip yoke to possible contamination or surface damage. Thus, it would be desirable to provide an improved protective cover for a slip yoke or other component that addresses this problem.
This invention relates to a two piece cover assembly for protecting a surface of a component, such as a slip yoke in a vehicle drive train assembly, during manufacturing and/or assembly. The cover assembly includes a tubular piece and a cap piece. The tubular piece has an inner surface that is adapted to fit over a hollow end portion of the slip yoke. The cap piece is removably attached to an end of the tubular piece such that the cap piece covers the splined inner surface of the slip yoke. In a preferred embodiment, the tubular piece and the cap piece each have retaining structures provided thereon that cooperate to removably retain the tubular piece and the cap piece together. The retaining structures can include mating external and internal ridges formed on the tubular piece and the cap piece, respectively. Alternatively, the tubular piece can include a circumferential groove formed therein, and the cap piece can include an annular ridge that extends inwardly into the groove to removably retain the tubular piece and the cap piece together.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.